Transcript Lecture #18 Date

Chapter 42
 Circulation
and Gas
Exchange
Circulation system evolution, I
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Gastrovascular cavity (cnidarians, flatworms)
Open circulatory •hemolymph (blood & interstitial
fluid) •sinuses (spaces surrounding organs)
Closed circulatory: blood confined to vessels
Cardiovascular system •heart (atria/ventricles)
•blood vessels (arteries, arterioles, capillary beds,
venules, veins) •blood (circulatory fluid)
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookcircSYS.html
Circulation system evolution, II
Earthworm http://yucky.discovery.com/noflash/worm/multi/heart.mov
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Fish: 2-chambered heart; single circuit of blood flow
Amphibians: 3-chambered heart; 2 circuits of blood flowpulmocutaneous (lungs and skin); systemic (some mixing)
Mammals: 4-chambered heart; double circulation; complete
separation between oxygen-rich and oxygen poor blood
Pulmonary/systemic
http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP12704
Double circulation
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From right ventricle to lungs
via pulmonary arteries
through semilunar valve
(pulmonary circulation)
Capillary beds in lungs to left
atrium via pulmonary veins
Left atrium to left ventricle
(through atrioventricular
valve) to aorta
Aorta to coronary arteries;
then systemic circulation
Back to heart via two venae
cavae (superior and inferior);
right atrium
Heart anatomy
http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP12504
The mammalian heart
Cardiac cycle http://msjensen.cehd.umn.edu/1135/Links/Animations/Flash/0028-swf_the_cardiac_cy.swf
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Cardiac cycle: sequence of filling
and pumping
Systole- contraction
Diastole- relaxation
Cardiac output: volume of blood
per minute
Heart rate- number of beats per
minute
Stroke volume- amount of blood
pumped with each contraction
Pulse: rhythmic stretching of
arteries by heart contraction
Blood flow
http://www.sumanasinc.com/webcontent/animations/content/human_heart.html
The heartbeat
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Sinoatrial (SA) node (“pacemaker”): sets rate and timing of
cardiac contraction by generating electrical signals
Atrioventricular (AV) node: relay point (0.1 second delay)
spreading impulse to walls of ventricles
Electrocardiogram (ECG or EKG)
Open heart surgery http://www.abc.net.au/science/lcs/swf/heart.swf
Blood vessel structural
differences
Capillary fluid exchange http://msjensen.cehd.umn.edu/1135/Links/Animations/Flash/0029-swf_fluid_exchange.swf
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Capillaries
•endothelium; basement
membrane
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Arteries
•thick connective tissue;
thick smooth muscle;
endothelium; basement
membrane
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Veins
•thin connective tissue;
thin smooth muscle;
endothelium; basement
membrane
The lymphatic system
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Lymphatic system: system
of vessels and lymph nodes,
separate from the circulatory
system, that returns fluid and
protein to blood
Lymph: colorless fluid,
derived from interstitial fluid
Lymph nodes: filter lymph
and help attack viruses and
bacteria
Body defense / immunity
Blood
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Plasma: liquid matrix of blood in which cells are suspended (90% water)
Erythrocytes (RBCs): transport O2 via hemoglobin
Leukocytes (WBCs): defense and immunity
Platelets: clotting
Stem cells: pluripotent cells in the red marrow of bones
Blood clotting: fibrinogen (inactive)/ fibrin (active); hemophilia; thrombus
(clot)
Cardiovascular disease
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Cardiovascular disease (>50% of
all deaths)
Heart attack- death of cardiac
tissue due to coronary blockage
Stroke- death of nervous tissue in
brain due to arterial blockage
Atherosclerosis: arterial plaques
deposits
Arteriosclerosis: plaque hardening
by calcium deposits
Hypertension: high blood
pressure
Hypercholesterolemia:
LDL, HDL
Gas exchange
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CO2 <---> O2
Aquatic: gills , ventilation , countercurrent exchange
Terrestrial: •tracheal systems •lungs
Mammalian respiratory systems
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Larynx (upper part of
respiratory tract)
Vocal cords (sound
production)
Trachea (windpipe)
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Bronchi (tube to
lungs)
Bronchioles
Alveoli (air sacs)
Diaphragm
(breathing muscle)
Breathing
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Positive pressure breathing: pushes air into lungs (frog)
Negative pressure breathing: pulls air into lungs (mammals)
Inhalation: diaphragm contraction; Exhalation: diaphragm relaxation
Tidal volume: amount of air inhaled and exhaled with each breath
(500ml)
Vital capacity: maximum tidal volume during forced breathing (4L)
Regulation: CO2 concentration in blood (medulla oblongata)
Respiratory pigments: gas transport
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Oxygen transportHemocyanin: found in
hemolymph of arthropods and
mollusks (Cu)
Hemoglobin: vertebrates (Fe)
Carbon dioxide transportBlood plasma (7%)
Hemoglobin (23%)
Bicarbonate ions (70%)
Deep-diving air-breathersMyoglobin: oxygen storing
protein
Respiratory System
Respiratory System
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Why do we need to
breathe?
Gas exchange
system
Requirements of
respiratory
membranes:
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must be moist.
Must be thin
must be
permeable to
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All organisms must
have a mechanism
with which to
transport gases.
(circulatory system)
Movement of gases
happens by simple
diffusion.
Surface Area and other
Respiratory Characteristics
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Cutaneous
Respiration
Examples
Why are our lungs
located within the
chest cavity and rib
cage?
Moisture
protection
Importance of
surface area.
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We have a
respiratory surface
area of about 60 to
70 square meters.
Human Respiratory Tract
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Nostrils
nasal septum
nasal cavity
Role of mucous
membranes and
hairs?
Pharynx
glottis
epiglottis
larynx
Adam’s apple
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Why is it so easy for
humans to choke?
Vocal cords
trachea
cartilage rings
incomplete rings
trachea
bronchi
bronchioles
alveoli
capillaries
How do we breathe?
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Thoracic cavity
pleura
pleurisy
diaphragm
intercostal muscles
Role of pressure
inspiration
What happens with
pressure and the
volume of the chest
cavity?
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Expiration
What happens with
pressure and the
volume of the chest
cavity?
Gas Exchange
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Where does it
occur?
What gases are
exchanged?
Simple diffusion is
responsible.
Erythrocytes
RBCs
Role of hemoglobin
Structure of
hemoglobin
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Oxyhemoglobin
4 oxygens at a
time.
Effects of CO
Carbon dioxide is
largely transported
as a dissolved gas
in the plasma
although some is
transported by
hemoglobin
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter25/animation__gas_exchange_during_respiration.html
Control of breathing
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Respiratory Center
Medulla Oblongata
Brainstem
Peripheral
Chemoreceptors
aorta and carotid
arteries
increase in Carbon
dioxide increases
H+ ion
concentration.
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Central
chemoreceptors in
the brain are
sensitive to this.
Increase CO2,
Increase breathing
rate.
Hyperventilation
Other mechanisms of
breathing
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Gills
Structure
Why do fish suffocate
on land?
Countercurrent flow
Insects
spiracles
tracheae
tracheoles
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Why can’t this work
in us?
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Snail and Frogs
Have lungs, but
very little
respiratory surface
area.
Cutaneous
Breathing.
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